The water beneath our feet

Measuring infiltration water in the Wombeyan Caves, New South Wales. Credit: Andrew Baker

converted into observatories to quantify how water moves through buried rock structures into groundwater.

Groundwater forms the world’s largest active repository of fresh water—more than a hundred times larger than rivers and lakes combined.

To use that groundwater resource sustainably, we need to know that we are only using as much water as is being continually replaced, mostly via rainfall and underground leakage from rivers.

University of New South Wales (UNSW) researchers are using their groundwater observatory to measure how much surface rainfall trickles through to recharge groundwater reserves. Recharge is governed by many factors, including rainfall, surface evaporation, and underground flow rates dependent on geological fractures and porosity.

Professor Andy Baker at UNSW is leading a research team that is the first to measure the rate and quantity of water that percolates through to caves from artificial ‘rainfall’ the team sprays onto the surface from large tanks.

His team’s findings will be crucial for models of groundwater flow used in resource planning. They will also contribute to our understanding of how contaminated water and pollutants move through the rocks beneath contaminated industrial sites.

Andy’s team is also using growth rings in stalagmites of subterranean caves to build a local climate history including rainfall, surface evaporation rates, the makeup of the soil above, and carbon markers of past wildfires.